try these guys out:

Soft Machine
Les Claypool (any of his projects though I do prefer Frog Brigade)
Grateful Dead (of fucking course)
Cream
Phish (live)
the Residents (woulnd't suggest to anyone who is not very very open minded to music)
Family Groove Company (a local band that really tripped me out live)
Medeski Martin & Wood (u gotta listen to them and give em a try)